1. Field of the Invention
The present invention relates generally to a negative pressure type magnetic head slider, and more particularly to a negative pressure type magnetic head slider for a load/unload type magnetic disk drive.
2. Description of the Related Art
In a recent magnetic disk drive, the flying height of a head slider from the surface of a magnetic disk is reduced more and more to increase a recording density. Further, a large acceleration is applied in an access direction to obtain a high access speed. It is accordingly desired to provide a head slider excellent in flying stability. Further, in association with size reduction of the disk drive and simplification of a mechanism in the disk drive, a rotary positioner is widely used. It is accordingly desired to provide a head slider in which variations in the flying height due to changes in yaw angle are suppressed.
To reduce the flying height of the head slider, the surface roughness of the surface of the magnetic disk must be reduced. In a contact start and stop (CSS) type magnetic disk drive heretofore widely used, a flying surface of a magnetic head slider comes into contact with a magnetic disk upon stoppage of rotation of the magnetic disk, and flies above the surface of the magnetic disk during rotation of the magnetic disk by the action of an air flow produced in concert with the rotation of the magnetic disk.
However, if the surface roughness of the magnetic disk in the CSS type magnetic disk drive is reduced, the contact area between the flying surface (air bearing surface) of the magnetic head slider and the surface of the magnetic disk upon stoppage of rotation of the magnetic disk becomes large. Accordingly, there is a possibility of stiction between the magnetic head slider and the magnetic disk at starting rotation of the magnetic disk. As measures against this stiction problem, it has been proposed to apply texture forming by laser to a CSS zone of the magnetic disk or provide a plurality of pads (projections) on the flying surface of the head slider in the CSS type magnetic disk drive.
A portable personal computer such as a notebook personal computer is often carried, and it is therefore required to have high shock resistance. Accordingly, such a personal computer generally employs a load/unload type magnetic disk drive designed so that a head slider is unloaded from the surface of a magnetic disk when the computer is powered off or put into a sleep mode and that the head slider is loaded to the surface of the magnetic disk when the computer is operated. That is, when the computer is powered off or put into a sleep mode, a horn portion formed at the front end of a suspension is seated on a ramp (inclined portion) of a ramp member provided near the outer circumference of the magnetic disk to retract the head slider flying a microscopic height above the disk surface from the magnetic disk. Accordingly, even when the computer receives shock, it is possible to avoid the possibility that the head slider may collide with the magnetic disk to damage the magnetic disk.
Such a magnetic disk drive having a load/unload mechanism is required to have a highly reliable magnetic head slider that is prevented from coming into contact or collision with a magnetic disk not only while the head slider is flying above the disk, but also when the head slider is loaded to the disk. A negative pressure type magnetic head slider is widely used in recent magnetic disk drives, so as to reduce the flying height of the magnetic head slider from the magnetic disk. As a negative pressure type magnetic head slider excellent in flying stability, there has been proposed a head slider in which a yaw angle dependence of flying height is reduced by increasing the widths of two rails from an air inlet end toward an air outlet end.
Further, variations in the flying height due to changes in yaw angle can be suppressed by reducing the width of a rail near the air inlet end. In these head sliders, a negative pressure (attraction force) is generated by changing only the width of each rail, thereby allowing simplification of a manufacturing process. Further, Japanese Patent Laid-open No. 2000-173217 includes a negative pressure type head slider which can further reduce the flying height, suppress variations in the flying height, and increase the rigidity.
In a recent magnetic disk drive, there is a tendency to reduce a magnetic disk spacing, in order to increase a storage capacity. To this end, the surface roughness of each magnetic disk is reduced, so that in the CSS type the stiction by the contact of the magnetic disk and the magnetic head slider in the rest condition becomes remarkable. To avoid this stiction problem, a load/unload type magnetic disk drive tends to be used not only in a portable personal computer such as a notebook personal computer, but also in a desktop personal computer.
A conventional negative pressure type magnetic head slider is mounted on a suspension so that the flying surface of the head slider becomes parallel to the magnetic disk at the instant when the head slider is loaded from the ramp member to the magnetic disk. Accordingly, there is a possibility that the head slider may come into contact with the disk because of a negative pressure generated on the head slider at the instant of loading.
Particularly in the case that a groove for generating a negative pressure is formed on the flying surface of the head slider so as to extend from a position upstream of the longitudinal center of the head slider to an air outlet end of the head slider, the head slider is inclined so that an air inlet end of the head slider is drawn to the magnetic disk by the negative pressure at the instant of loading, causing the contact of the air inlet end with the magnetic disk. To prevent this problem, there has been proposed a magnetic head slider mounted on a gimbal bent from a suspension so that the disk opposing surface of the head slider is inclined with respect to the disk surface at a given pitch angle in such a direction of raising the air inlet end from the disk surface. This pitch angle is set in the range of 1xc2x0xc2x11xc2x0, for example.
In the case that the angle of incidence of the magnetic head slider mounted on the gimbal falls outside the above range, a negative pressure is generated on the magnetic head slider upon loading and the air inlet end of the head slider is rapidly lowered to cause a possibility of the contact of the air inlet end and the disk. To avoid this problem, there has been proposed a head slider in which a step surface formed on the disk opposing surface at a portion near the air inlet end is cut to form a groove for generating a positive pressure near the air inlet end in the case of loading the head slider at a negative pitch angle.
However, when the step surface is cut, the flying attitude of the head slider largely changes. Particularly, a peripheral speed dependence of pitch angle becomes large. This is due to the fact that the pressure at the air inlet end becomes unsaturated at low peripheral speeds because of cutting of the step surface. Accordingly, a reduction in negative pressure and rigidity occurs. Further, there occurs a reduction in performance such that a flying loss (a difference in level between a lowest flying point of the slider and a flying point of the head element) becomes large because of an increase in pitch angle depending on a peripheral speed.
It is therefore an object of the present invention to provide a negative pressure type magnetic head slider which can avoid the collision with a magnetic disk upon loading and can suppress the peripheral speed dependence of pitch angle.
In accordance with an aspect of the present invention, there is provided a head slider having a disk opposing surface, an air inlet end, and an air outlet end, the head slider comprising a front rail formed on the disk opposing surface in the vicinity of the air inlet end, the front rail having a first air bearing surface and a first step surface lower in level than the first air bearing surface; a transducer formed in the vicinity of the air outlet end; a first groove for expanding air once compressed by the front rail to generate a negative pressure; and a second groove formed on the first step surface near the air inlet end except opposite side portions of the first step surface; the first step surface reaching the air inlet end at the opposite side portions.
Preferably, each of the opposite side portions of the first step surface has a width less than or equal to 200 xcexcm. More preferably, the width of each side portion is in the range of 50 to 150 xcexcm. Preferably, the head slider further comprises a rear center rail formed on the disk opposing surface in the vicinity of the air outlet end at a substantially central position in the lateral direction of the head slider, the rear center rail having a second air bearing surface and a second step surface lower in level than the second air bearing surface; the transducer being formed on the second air bearing surface of the rear center rail near the air outlet end.
In accordance with another aspect of the present invention, there is provided a head slider having a disk opposing surface, an air inlet end, and an air outlet end, the head slider comprising a front rail formed on the disk opposing surface in the vicinity of the air inlet end, the front rail having a first air bearing surface and a first step surface lower in level than the first air bearing surface; a transducer formed in the vicinity of the air outlet end; a first groove for expanding air once compressed by the front rail to generate a negative pressure; and a pair of second grooves formed on the first step surface near the air inlet end except a laterally central portion of the first step surface; the first step surface reaching the air inlet end at the laterally central portion.
Preferably, the first step surface reaches the air inlet end also at opposite side portions of the first step surface. In this case, the laterally central portion has a width less than or equal to 700 xcexcm, and each of the opposite side portions has a width less than or equal to 200 xcexcm. More preferably, the width of the laterally central portion is in the range of 500 to 700 xcexcm, and the width of each side portion is in the range of 50 to 150 xcexcm.
Preferably, the head slider further comprises a rear center rail formed on the disk opposing surface in the vicinity of the air outlet end at a substantially central position in the lateral direction of the head slider, the rear center rail having a second air bearing surface and a second step surface lower in level than the second air bearing surface; the transducer being formed on the second air bearing surface of the rear center rail near the air outlet end.
In accordance with a further aspect of the present invention, there is provided a disk drive comprising a housing having a base; a negative pressure type head slider having a transducer for reading/writing data from/to a disk having a plurality of tracks, an air inlet end, and an air outlet end, and a disk opposing surface; an actuator for moving the negative pressure type head slider across the tracks of the disk; means for controlling the actuator to load/unload the negative pressure type head slider to/from the disk; and a ramp member fixed to the base for supporting the negative pressure type head slider unloaded from the disk; the actuator comprising an actuator arm rotatably mounted on the base; a suspension fixed at a base end portion thereof to a front end portion of the actuator arm; and the negative pressure type head slider mounted on a front end portion of the suspension; the negative pressure type head slider comprising a front rail formed on the disk opposing surface in the vicinity of the air inlet end, the front rail having a air bearing surface and a step surface lower in level than the air bearing surface; a transducer formed in the vicinity of the air outlet end; a first groove for expanding air once compressed by the front rail to generate a negative pressure; and a second groove formed on the step surface near the air inlet end except opposite side portions of the step surface; the step surface reaching the air inlet end at the opposite side portions.
The second groove may be replaced by a pair of second grooves formed on the step surface near the air inlet end except a laterally central portion of the step surface. In this case, the step surface reaches the air inlet end at the laterally central portion.
In each configuration mentioned above, the step surface reaches the air inlet end. Accordingly, even if the head slider comes into contact with a disk medium upon loading, the relatively broad end of the step surface formed by photolithography rather than a sharp edge of the step surface formed by cutting comes into contact with the disk medium, thereby exhibiting an additional effect that the damage to the disk medium due to the contact of the head slider and the disk medium upon loading can be reduced.
The above and other objects, features and advantages of the present invention and the manner of realizing them will become more apparent, and the invention itself will best be understood from a study of the following description and appended claims with reference to the attached drawings showing some preferred embodiments of the invention.